Optical Coupler Package Dam Structure
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Solution Overview
Problem
The manufacturing of optical coupler packages faces challenges with glob top overflow onto solder pads during the curing process, which can prevent the proper placement of solder balls and necessitate additional process steps and increased costs, as existing methods lack effective containment mechanisms.
Innovation Solution
The use of a molding compound that forms a dam structure integral to the leadframe, confining the glob top and preventing overflow, while also providing a substrate with an optically transmissive medium between the optical emitter and receiver, and conductive structures for solder ball anchoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a glob top is deposited to protect optical devices, then device protection is improved, but glob top overflow onto solder pads occurs causing manufacturing defects
Solution Approach 1:
The patent segments the molding compound application by creating a dam structure that divides the packaging area into a device protection zone and a solder pad zone. This segmentation allows the glob top to be contained within the dam structure, protecting optical devices without overflowing onto solder pads.
Solution Approach 2:
The dam structure is formed preliminarily before depositing the glob top material. This preliminary action creates containment boundaries that prevent subsequent glob top overflow, eliminating the need for rework and ensuring proper solder ball placement.
2Manufacturing precision
If a separate dam structure is deposited to confine glob top, then overflow prevention is improved, but process complexity and cost increase
Solution Approach 1:
The patent merges the dam structure formation with the existing substrate preparation process. The dam structure is integrated into the substrate itself, combining multiple functions (substrate support, glob top containment, solder pad definition) into a single component, thereby reducing overall process complexity.
Solution Approach 2:
The dam structure serves multiple functions simultaneously: it confines the glob top material, defines the device mounting area, and provides structural support. This multi-functionality eliminates the need for separate confinement structures and reduces the overall number of process steps.
3Reliability
If glob top overflows onto pads, then rework is needed, but manufacturing time and cost increase
Solution Approach 1:
The dam structure is formed in advance to prevent glob top overflow before it can occur during the curing process. This preliminary anti-action eliminates the need for subsequent rework operations, maintaining manufacturing efficiency and productivity.
Data Source
AI summary
A method is disclosed. The method includes forming a substrate with a leadframe and a molding compound. The molding compound fills internal spaces in the leadframe and forms a dam structure. An optical emitter and an optical receiver are placed on the substrate. An optically transmissive medium is formed between the optical emitter and optical receiver.